Improved piston for steam-engines



IIN ITED STATES PATENT Ormea.

SAMUEL M. SELEY AND PETER HOPKINS, OF PEORIA, ILLINOIS.

INIPROVED PISTON FOR STEAM-ENGINES Specilication forming part of Letters Patent No. 35,7 l l, dated June 24, 1862.

Figure 1 is a perspective view of our im proved piston with the follower-plate removed to expose the interior. Fig. 2 is a longitudinal section of the piston complete.

Similar letters of reference indicate corresponding parts in the several views.

The nature of our invention consists in a` peculiar construction and arrangement of internal valves for admitting steam to the interior of the piston in order to expand the packing-rings, as hereinafter explained.

To enable others skilled in the art to which our invention pertains to make and use the same, we will proceed to describe its construction and operation.

Arepresents the mainfollower or pistonhead attached to the rod B in customary manner.

C is a movable follower-plate attached to the head A by bolts D D, screwed into holes d.

E E are pins lor studs fixed in the head A and projecting so far as to enter sockets prepared for them in the movable followerplate C, as clearly shown in Fig. 2. Circular valveseats S S' are formed around the pins E in the inner face of each plate A and C, which seats are perforated each with one, two, or more holes, s s. Y

F F are valves fitted loosely upon the pins E, so that they may be adapted to'close the apertures in either valve-seat S or S', as hereinafter explained. The said valves may be made each of a single piece of metal; but we prefer to construct each in two pieces, as shown in the sectional View, Fig. 2, in order that a washer, f, may be inserted between them, when needful to compensate for the wear or grinding ofthe faces of the valves.

G is an inner packing-ring, divided at g, and of suflcient width to extend from face to face of the plates A and C.

H I are outer packing-rings, divided at h i, and having a combined width equal to the width of the inner ring, G. A stud or projection, g', upon the periphery of the inner ring, G, tits in corresponding slotsin the inside surfaces of the rings H and I, so as to prevent any two of the joints g, h, and 'i from coming together.

h i are tongues secured to one part of each ring H I, and projecting under the joints h. 'i in such a manner as to prevent any escape of steam, and at the same time permit thefree contraction and expansion ot' the rings.

We prefer to construct the packing-rings and valves of cast-iron, to combine cheapness and durability, so far as practicable. lThey may, however, be made of brass or any other suitable material. The pins E are by preference formed of steel; but we do not restrict ourselves to this particular metal.

rIhe valves F are made of such depth as to have a motion of about one thirtysecond of an inch. They may be made about one and iiveeighths inch in diameter and the seats about one and three-fourths inch. The invention is found to operate with good success with four valves, each covering three three-eighthsinch holes in each plate. By using siX holes instead of three in each valveseat two valves will suffice.

In the original construction of a piston after our invention we prefer to make it in the form represented. We do not, however, desire to be understood as restricting ourselves thereto. The outer ring may, if preferred, be made in one and the inner ring dispensed with entirely, the tongue h t' making an effective steam-tight joint. The invention is equally applicable to pistons in common use, and may be applied in either case at a tritling cost and the valves admit of being readily repaired or replaced when worn. The valve-seats are cut simultaneously in both plates by means of a right and left rose-bit of peculiar construction operated by a ratchet. Accurate and uniform seats are thus provided for both ends of the valves. Holes of any size are bored simultaneously in the corresponding seats of both plates by means of a suitable drill.

The operation of theinvention will be readily understood from the drawings. Steam being admitted behind the piston, so as to move it in the direction indicated by the arrow in Fig. 2, the valves will be thrown against the plate C, thereby opening the ports s s and admitting the full pressure of' steam Within the piston, but closing the ports s' s', to as to prevent the escape of live steam into the exhaust. This pressure of steam expands the packing-rings in custoinany manner, and is maintained by steam entering the ports s or s on eithei1 side, on which the excess of pressure may be, the ports on the opposite side being' closed, as before explained.

Having thus described our invention, what We claim as new therein, and desire to secure by Letters Patent, isy 

